Differentiated PSIP table update interval technology

ABSTRACT

An apparatus, method and data structure for generating at least one table in a broadcast environment, are provided. The apparatus includes a generator to generate an event information table (EIT) and an extended text table (ETT). The ETT has program guide information for an n-hour span and has a transmission interval. The ETT has a transmission interval and program description information according to the EIT. The transmission interval of the EIT is shorter than the transmission interval of the ETT.

The present application is a continuation of co-pending Application No.091828.865 filed on Apr. 10, 2001, and for which priority is claimedunder 35 U.S.C. § 120, the entire contents of which are herebyincorporated by reference. The present application also claims priorityupon U.S. Provisional Patent Application Ser. No. 60/197,677, filed Apr.17, 2000, the entirety of which is hereby incorporated by reference.

FIELD OF THE INVENTION

The invention is directed toward the field of digital television signalmeta data generation, and more particularly to the non-uniform issuanceof certain tables included within such meta data.

BACKGROUND OF THE INVENTION

It is known for a digital television (DTV) signal to Include meta datarepresenting information about the contents of the events, e.g.,programs, movies, sports games, etc. contained in the DTV signal. For aterrestrially broadcast DTV signal, the Advanced Television StandardsCommittee (ATSC) has promulgated the A/65 Standard that defines suchmeta data. The A/65 standard refers to such meta data as program andsystem information protocol (PSIP) data.

The PSIP type of meta data is issued periodically. Data of greaterimportance in the meta data hierarchy is inserted into the DTV signalmore frequently than data of lower importance.

In general, in this art it is desired to maximize the amount ofavailable bandwidth that can be allocated to the transmission of the DTVprogram content. Unfortunately, meta data consumes bandwidth thatotherwise could be used to transmit the corresponding DTV programcontent But such meta data is a prerequisite to an A/65 compliant DTVsignal, hence it cannot be eliminated to recover bandwidth.

It is a problem to reconcile the contradictory design criteria ofmaximizing bandwidth allocated to DTV program content and providingsufficient meta data to ensure compliance with the A/65 standard.

SUMMARY OF THE INVENTION

The invention is, in part, a solution to the problem of how to insertthe least amount possible of meta data into the DTV signal and yet stillachieve an A/65 compliant DTV signal. In other words, the invention is,in part, a recognition that it is desirable to insert meta data into theDTV signal as infrequently as possible.

The invention is, also in part, a recognition that the A/65 standardestablishes fixed frequencies of table output for some of the programand system information protocol (PSIP) data tables, e.g., such as theMaster Guide Table (MGT), the Virtual Channel Table (VCT) and the SystemTime Table (STT), but not for some others; and such unfixed outputintervals afford opportunities to lessen meta data output therebyreducing bandwidth consumption In the form of PSIP meta data withoutsacrificing compliance with the A/65 standard.

The invention provides, in part, a method to determine issuanceintervals for like-types of tables, respectively, in a digitaltelevision packet stream having a plurality of different types of tablesthat do not have issuance intervals set by a governing standard. Such amethod comprises: setting issuance intervals for like ones of thenon-governed tables, respectively, to be non-uniform. Such non-uniformissuance intervals can be determined as a function of at least one of anamount of time in the future to which the table corresponds and a degreeof probable interest-to a viewer. Further, such non-uniform issuanceintervals can be weighted so that an issuance interval for a tablecorresponding to a time nearer the present is smaller than an issuanceinterval corresponding to a time further in the future.

Examples of meta data PSIP tables that can benefit from the methodaccording to the invention include extended text tables (ETTs) and eventinformation tables (EITs).

Each issuance interval between any two instances of an i^(th) table canbe determined according to the following equation:

interval(i ^(th) table)=root_lime+(increment_time)*i

where interval(i^(th) table) is the interval between any two instancesof the i^(th) table, root_time is a predetermined interval for the tablecorresponding most closely in time to the present, increment_time is anon-zero scalar and i is a non-zero Integer.

The invention, also in part, provides a program and system informationprotocol (PSIP) generator to generate tables for a digital televisionsystem packet stream, the generator comprising: an interface to receiveat least one issuance parameter for like tables that do not all have anissue interval assigned by a governing standard; and a non-uniforminterval calculation unit to determine non-uniform issuance intervalsfor unassigned-interval-ones of said like tables based upon said atleast one issuance parameter. Such a PSIP generator embodies the methodaccording to the invention, e.g., as described herein.

The invention, also in part, provides a processor-readable article ofmanufacture having embodied thereon software comprising a plurality ofcode segments to cause a processor to perform the method according tothe invention.

According to an aspect of the invention, there is provided an apparatusfor generating at least one table in a broadcast environment, theapparatus comprising: a generator to generate an event information table(EIT) and an extended text table (ETT), the ETT having program guideinformation for an n-hour span and having a transmission interval, theETT having a transmission interval and having program descriptioninformation according to the EIT, wherein the transmission interval ofthe EIT is shorter than the transmission interval of the ETT.

According to an aspect of the invention, there is provided a method forgenerating at least one table in a broadcast environment, the methodcomprising: generating an event information table (EIT) and an extendedtext table (ETT), the ETT having program guide information for an n-hourspan and having a transmission interval, the ETT having a transmissioninterval and having program description information according to theEIT, wherein the transmission interval of the EIT is shorter than thetransmission interval of the ETT.

According to an aspect of the invention, there is provided a datastructure for generating at least one table in a broadcast environment,the structure comprising: an event information table (EIT) havingprogram guide Information for an n-hour span and having a transmissioninterval; and an extended text table (ETT) having a transmissioninterval and having program description information according to theEIT, wherein the transmission interval of the EIT is shorter than thetransmission interval of the ETT.

Advantages of the present invention will become more apparent from thedetailed description given hereinafter. However, it should be understoodthat the detailed description and specific examples, while indicatingpreferred embodiments of the invention, are given by way of illustrationonly, since various changes and modifications within the spirit andscope of the invention will become apparent to those skilled in the artfrom this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus do not limit thepresent invention.

FIG. 1 is a block diagram of a PSIP generator according to the inventionin the context of typical inputs to it and outputs from it.

FIG. 2 is an image of a dialog window within a screen of a graphicaluser interface (GUI) generated by the PSIP data generator according tothe invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

FIG. 1 is a block diagram of a program and system information protocol(PSIP) data generator according to the invention in the context ofsystem 100 that can produce an Advanced Television Standards Committee(ATSC), standard A/65, compliant digital television (DTV) signal. Thesystem 100 of FIG. 1 includes: a PSIP generator 102 according to theinvention; sources of data upon which the PSIP generator operates, suchas a source 108 of listing service data, a source 110 of traffic systemdata and a source 112 of other data; a multiplexer 114 to incorporatethe PSIP data from the PSIP generator 102 into an A/65-compliant DTVsignal; and a source 116 of audio data, video data, etc.

In FIG. 1, the PSIP generator 102 includes an interface unit 104 and anon-uniform interval calculation unit 106.

The PSIP generator 102 according to the invention can be implemented byadapting a well known PSIP generator according to the discussion herein.An example of a known PSIP generator is the PSIP BUILDER PRO brand ofPSIP generator manufactured and sold by TRIVENI DIGITAL INC. The PSIPBUILDER PRO itself is based upon a programmed PC having a Pentium typeof processor using the MICROSOFT WINDOWS NT4.0 operating system. Thesoftware can be written in the Java language. The other blocks of FIG. 1correspond to known technology.

In FIG. 1, the invention has been depicted in the context of a digitaltelevision broadcast such as a terrestrial broadcast, and moreparticularly one that is compliant with the Advanced TelevisionStandards Committee (ATSC), where each event is a program, and theschedule data is PSIP data. However, the invention is readily applicableto any television format, e.g., analog terrestrial, analog cable,digital cable, satellite, etc., for which an electronic schedule ismaintained and corresponding data is sent to a receiver for the purposeof presenting an electronic program guide (EPG) to a viewer.

The units 104 and 106 within the PSIP generator 102 do not necessarilycorrespond to discrete hardware units. Rather, the units 102 and 104 canrepresent functional units corresponding to program segments of thesoftware that can embody the invention.

The interface unit 104 can generate a graphical user interface (GUI)that operates to receive at least one, issuance parameter for like PSIPtables (e.g., ETTs or EITs) that do not all have an issue intervalassigned by the A/65 standard. Such an interface will be described inmore detail below with regard to FIG. 2. The non-uniform intervalcalculation unit 106 is operable to determine non-uniform issuanceintervals for ones of the like PSIP tables that do not have an assignedinterval, based upon the issuance parameter(s) received via theinterface unit 104.

FIG. 2 is an example image of a dialog window 200 (a GUI) that can begenerated by the interface unit 104 according to the invention. In FIG.2, the dialog window 200 can include: a Cycle Time Settings tab 202; aMiscellaneous Settings tab 204; a FTP Periodic Update Controls tab 206;an “Apply Settings” button 226; a “Defaults” button 228; a “Refresh”button 230; and a “Close” button 232. The position of the cursor can beIndicated via the reverse highlighting 234. The Cycle Time Settings tab202 can include a “Cycle Times (in seconds) for EITs:” region 208, a“Cycle Times (in seconds) for PSIP Tables:” region 210, a “Cycle Times(in seconds) for PSI Tables:” region 212 and a “Cycle Times (in seconds)for ETTs.” region 214.

It is well known that EITs carry program schedule information includingprogram title information and program start information. Each EIT coversa three-hour time span. ETTs carry text messages associated with theEITs, e.g., program description information for an EIT.

In FIG. 2. the “Cycle Times (in seconds) for EITs:” region 208 of thedialog window 200 can include: a box 216 in which a user can enter afixed Interval for the EIT₀ table; a box 218 in which a user can enteran increment for the EIT_(k) table; and a box 220 in which a user canenter a maximum number of EIT tables that are to be sent. Usually, thenumber entered in box 220 will be far smaller than the maximum number ofEIT tables permitted by the A/65 standard.

Also, in FIG. 2. the “Cycle Times (in seconds) for ETTs:” region 214 caninclude: a box 222 in which a user can enter a fixed interval for theETT₀ table; and a box 224 in which a user can enter an increment for theETT_(k) table.

The non-uniform interval calculation unit 106 can receive the values inthe boxes 216, 218, 220, 222 and 224 from the regions 208 and 214,respectively, and use them to determine the non-uniform issuanceintervals of, e.g., the EIT and ETT tables. Further discussion of theoperation of the unit 106 is couched in a particular non-limitingexample, for simplicity.

The A/65 standard recommends a time interval for outputting the zeroithEvent Information Table (EIT), I.e., EIT₀, but provides no guidelinesregarding EIT₁ through EIT₁₂₈. For the Rating Region Table (RRT), theA/65 standard recommends a value only for the output frequency of RRT₁.And no recommendation is made regarding the output frequencies of any ofthe Extended Text Tables (ETTs).

Under the A/65 standard, it is left to the discretion of the operator ofa PSIP data generation system to select the frequency of table outputfor the unmentioned tables. The operator could specify an entry for eachgroup of tables, but that would be burdensome because it would require atotal of over 500 entries. A simple solution to the problem ofunspecified output frequencies would be to set each type of table to thesame output frequency, but that creates a problem in that the guidelinesfor bandwidth specified by the A/65 standard would be exceeded.

A further consideration to solve the problem, namely of how to insertthe least amount possible of meta data into the DTV signal and yet stillachieve an A/65 compliant DTV signal, is: How closely in time to thepresent moment does each table relate? That is, table types such as theEIT describe event information up to two weeks into the future. A userof an electronic program guide that receives such table types willtypically want to view event information concerning only the next 24-48hours. Users typically do not look farther into the future than thisbecause (at least in part) the event schedule information two weeks intothe future is much more likely to change than is event scheduleinformation concerning the next 24-48 hours, i.e., the farther into thefuture. the less reliable the event information becomes.

Care must be exercised so as not to set the intervals to be tooinfrequent. This is because the DTV receiver can become stalled waitingfor a table to arrive. If the DTV receiver is stalled for 0.5 seconds, auser might not notice or object if she did. But such a delay of, e.g.,4-5 seconds probably would be noticed by, and probably would annoy, theuser. This reinforces the need to set short intervals for near termevents because users are likely to want to display EPG information aboutthem.

Again, the invention, in part, provides an interface unit 104 thatdefines parameters that the non-uniform interval calculation unit 106then can use to generate the time intervals between tables of the sametype. Typically (but not necessarily) the function performed by the unit106 will be linear, e.g., with a defined start interval (the root_time)and an increment interval (increment_time). For example, if the userdesires EIT₀ to be output every half second (root time) with eachsucceeding EIT₀ to be output 0.25 seconds less frequently than thepreceding EIT, namely EIT_(I) the user would enter 0.5 seconds as theroot_time in box 216 and 0.25 seconds as the increment_time in box 218.The function for each table EIT-i interval would then be:

Time  between  any  two  instances  of  table_(i) = root_time + (increment_time * i) = 0.5  sec  + (0.25  sec  * i)

For example, EIT₁₂ can be output every 0.5 sec+(0.25 sec*12)=3.5seconds, which is less frequent than EIT₀. Obviously, other examples arepossible, e.g., the increment_time for each of different groups of liketables can be set.

A similar calculation for ETTs can be performed by the unit 106.

The invention has at least the following advantages: 1) it provides aneasy way of entering the interval times for the tables: 2). it definesthe interval times for like tables that are not all fixed to a constantinterval; and 3) it provides an interval function that increases theinterval for tables that represent information further out in time.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1-20. (canceled)
 21. A method to optimize a bandwidth of a digitaltelevision (DTV) transport stream and to determine transmission cyclesfor tables to be transmitted as part of the DTV transport stream, themethod comprising: setting transmission cycles for a sequence of eventinformation tables EIT0, EIT1, EIT2, and EIT3 containing programinformation covering different time spans, wherein the transmissioncycle of the EIT0 is less than the transmission cycle of the EIT1; andsetting transmission cycles for a sequence of extended text tables ETT0,ETT1, ETT2, and ETT3 containing program description informationassociated with the EIT0, EIT1, EIT2, and EIT3, respectively, whereinthe transmission cycle of the ETT3 is greater than a sum of thetransmission cycle of the EIT0 and the transmission cycle of the EIT1,wherein the transmission cycle of the ETT3 is equal to the transmissioncycle of the EIT3.
 22. The method of claim 21, wherein each of thedifferent time spans is a 3 hour time span.
 23. The method of claim 21,wherein the program information includes program guide informationhaving at least program time information and program start timeinformation.
 24. The method of claim 21, further comprising:broadcasting the DTV transport stream having the EITs and ETTs thereinto receiving devices.
 25. The method of claim 21, wherein thetransmission cycle of the EIT0 is 0.5 seconds.
 26. A method of operatinga digital television (DTV) receiver that receives and processes a DTVtransport stream, the method comprising: receiving in a DTV transportstream a sequence of event information tables EIT0, EIT1, EIT2, and EIT3containing program information covering different time spans, wherein arepetition cycle of the EIT0 is less than a repetition cycle of theEIT1; parsing the EIT0, EIT1, EIT2, and EIT3 from the DTV transportstream; receiving in the DTV transport stream a sequence of extendedtext tables ETT0, ETT1, ETT2, and ETT3 containing program descriptioninformation associated with the EIT0, EIT1, EIT2, and EIT3,respectively, wherein a repetition cycle of the ETT3 is greater than asum of the repetition cycle of the EIT0 and the repetition cycle of theEIT1; and parsing the ETT0, ETT1, ETT2, and ETT3 from the DTV transportstream, wherein the repetition cycle of ETT3 is equal to a repetitioncycle of the EIT3.
 27. The method of claim 26, wherein each of thedifferent time spans is a 3 hour time span.
 28. The method of claim 26,wherein the program information includes program guide informationhaving at least program time information and program start timeinformation.
 29. The method of claim 26, wherein the repetition cycle ofthe EIT0 is 0.5 seconds.